Communications satellites in the context of "Satellite constellation"

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⭐ Core Definition: Communications satellites

A communications satellite is an artificial satellite that relays and amplifies radio telecommunication signals via a transponder; it creates a communication channel between a source transmitter and a receiver at different locations on Earth. Communications satellites are used for television, telephone, radio, internet, and military applications. Some communications satellites are in geostationary orbit 22,236 miles (35,785 km) above the equator, so that the satellite appears stationary at the same point in the sky; therefore the satellite dish antennas of ground stations can be aimed permanently at that spot and do not have to move to track the satellite. But most form satellite constellations in low Earth orbit, where antennas on the ground have to follow the position of the satellites and switch between satellites frequently.

The radio waves used for telecommunications links travel by line of sight and so are obstructed by the curve of the Earth. The purpose of communications satellites is to relay the signal around the curve of the Earth allowing communication between widely separated geographical points. Communications satellites use a wide range of radio and microwave frequencies. To avoid signal interference, international organizations have regulations for which frequency ranges or "bands" certain organizations are allowed to use. This allocation of bands minimizes the risk of signal interference.

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Communications satellites in the context of Launch cost

Space launch market competition is the manifestation of market forces in the launch service provider business. In particular it is the trend of competitive dynamics among payload transport capabilities at diverse prices having a greater influence on launch purchasing than the traditional political considerations of country of manufacture or the national entity using, regulating or licensing the launch service.

Following the advent of spaceflight technology in the late 1950s, space launch services came into being, exclusively by national programs. Later in the 20th century commercial operators became important customers of launch providers. International competition for the communications satellite payload subset of the launch market was increasingly influenced by commercial considerations. However, even during this period, for both commercial- and government-entity-launched commsats, the launch service providers for these payloads used launch vehicles built to government specifications, and with state-provided development funding exclusively.

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Communications satellites in the context of Molniya (satellite)

The Molniya (Russian: Молния, IPA: [ˈmolnʲɪjə] , "Lightning") series satellites were military and communications satellites launched by the Soviet Union from 1965 to 1991, and by the Russian Federation from 1991 to 2004. These satellites used highly eccentric elliptical orbits known as Molniya orbits, which have a long dwell time over high latitudes. They are suited for communications purposes in polar regions, in the same way that geostationary satellites are used for equatorial regions.

There were 164 Molniya satellites launched, all in Molniya orbits with the exception of Molniya 1S which was launched into geostationary orbit for testing purposes.

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Communications satellites in the context of Naval Space Command

The Naval Space Command (NSC) was a military command of the United States Navy and former component command of United States Space Command. It was headquartered at Dahlgren, Virginia, and began operations on 1 October 1985. Naval Space Command used space capabilities to support naval forces through the operation of reconnaissance and communications satellites, as well as representing the Navy's space interests, both within the Navy and within U.S. Space Command.

The command was merged into Naval Network and Space Operations Command, itself part of Naval Network Warfare Command, about July 2002.

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